In the lighting industry, the use of light emitting diodes (LEDs) has provided numerous benefits over the conventional lighting sources in a variety of applications. In particular, lamps have used LEDs as a light source to increase efficacy, i.e., lumens-per-watts (LPW), as compared to, for example, the relatively inefficient incandescent and fluorescent lamps. As such, LEDs may generally provide greater energy efficiency and increased lifespan. In addition, LEDs may also provide a greater range of controllability. For example, some LED-equipped lighting systems can be controlled so as to produce a range of different properties of light, adjustable to users' requirements for a particular application and/or setting.
Some light control systems, in addition to varying light levels (i.e. dimming), may be configured to manipulate the spectral composition of an LED light source to effectively alter the main chromatic properties of the light source. The chromatic properties may include, for example, the appearance of the light source based on brightness and color temperature. The brightness, or illumination level, is a measure of the amount of useable light which is incident on a surface of an object. Color temperature, also referred to herein as correlated color temperature (CCT), is a description of color appearance of a light source in terms of its warmth or coolness. Light sources with a low color temperature generally have a yellow-white color and are described as “warm,” while lamps with a high color temperature have a blue-white color and are described as “cool.”
While brightness and color temperature are indicators of the color appearance of light, neither describes the mix of wavelengths present an LED light source, an important factor when illuminating objects. Color rendering, another chromatic property of light, is a measure of the quality of light emitted by a light source with regard to the light source's ability to effectively reproduce the color of an illuminated object. As generally understood, the perceived color of an object depends, in part, on the wavelengths emitted by the light source and the wavelengths reflected and absorbed by the object. Generally, an object has reflectance properties, whereby each wavelength in the spectrum of light imparted upon the object is absorbed or reflected to a varying extent. An object will selectively absorb or reflect the wavelengths from the light source, which, in turn, results in a perceived appearance (e.g. color) of the object. As such, the perceived color of an object is highly dependent on the light source and the associated color rendering properties of the light source.
Most applications and settings generally utilize white light for illumination purposes. In recent years, white LEDs have quickly matched and overtaken the efficacy of standard incandescent and fluorescent lighting systems. A challenge in controlling white LED lighting is that, in certain settings and applications, light must be continuously perceived by users as white. However, manipulation of and effects applied to the LED lighting can disturb a user's overall visual experience within a setting.
For a thorough understanding of the present disclosure, reference should be made to the following detailed description, including the appended claims, in connection with the above-described drawings. Although the present disclosure is described in connection with exemplary embodiments, the disclosure is not intended to be limited to the specific forms set forth herein. It is understood that various omissions and substitutions of equivalents are contemplated as circumstances may suggest or render expedient. Also, it should be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.